An input device is a peripheral used to provide data and control signals to an information processing system such as a computer or other information appliance. The peripheral may be a hardware equipment, integral to a computing device or coupled thereto.
Input devices can be classified according to their modality of input (e.g., mechanical motion, audio, visual, etc.), number of degrees of freedom involved, and the type of digital or analogue input. For example, a touchscreen is an electronic visual display that can detect the presence and location of a touch (e.g., of a finger, hand, or a stylus) within the display area. A touchpad (or trackpad) is a pointing device featuring a tactile sensor, a specialized surface that can translate the motion and position of a user's fingers to a relative position on screen. A mouse is a pointing device that functions by detecting two-dimensional motion relative to its supporting surface. The mouse's motion typically translates into the motion of a pointer on a display, which allows for fine control of a graphical user interface.
Input devices can interact with graphical user interfaces directly (e.g., when using a touchscreen) or indirectly (e.g., when using a touchpad or a mouse).